In a mobile communication network, after a phone call is finished, the user equipment (UE) releases the connection with the base station (and the upper node) and changes its mode from a connected mode (an active mode) to a waiting mode (an idle mode). In the waiting mode (the idle mode), the network does not manage nor register the cell where the user equipment is located but does manage and register the tracking area (TA) where the user equipment is located. The Tracking area (TA) may also be referred to as a location registration area, a routing area (RA), or the like, and, when a call is placed to the user equipment, paging is performed throughout the registered tracking area.
FIG. 1 schematically shows a case where a first tracking area TA1 includes three cells (cell 1, cell 2, and cell 3) and a second tracking area TA2 includes two cells (cell 4 and cell 5). Each of the base stations of the cells broadcasts the cell identification (cell ID) and the tracking area identification (TA-ID) via (using) the broadcast information (broadcast channel) (BCH). Next, a case is considered where the user equipment (UE) in the waiting mode (the idle mode) and in the cell 1 moves and accordingly performs a cell reselection by selecting the cell 3 as a waiting cell. In the process of the cell reselection, the user equipment (UE) receives the broadcast channel (BCH) from the base station of the cell 3 and checks the cell identification (cell ID) and the tracking area identification (TA-ID) included in the broadcast channel (BCH). As a result of the check, in the case of FIG. 1, the user equipment (UE) determines that both the cell 1 and the cell 3 belong to the same tracking area (TA1). Since there is no change of the tracking area, even when the user equipment (UE) performs the reselection of (reselects) the cell 3 and changes the cell to be selected from the cell 1 to the cell 3 in such a case like this, the user equipment does not issue a request to update the registration of the tracking area. Further, a case is considered where the user equipment (UE) further moves from the cell 3 into the cell 5 while keeping its waiting mode (the idle mode). In this case, the user equipment (UE) receives the broadcast channel (BCH) from the base station of the cell 5 and determines that the tracking area has changed from TA1 to TA2. In response to this change, the user equipment (UE) issues the request to update the registration of the tracking area to the base station of the cell 5, so that an update registration process of the tracking area (TA update) is performed. After this TA update, when a call is placed to the user equipment (UE), paging is performed for the user equipment (UE) throughout the tracking area TA2. As is described, the update registration of the tracking area is performed based on the request from user equipment (UE).
Recently, a mobile communication network called a private network (P-NW) as shown in FIG. 2 has been becoming more popular. For example, such a private network (P-NW) may include a mobile communication network to be used for only the staff members of a company organization within the facility of the company. The user equipment of the company staff members may communicate by using the private network within the facility of the company and by using a public network (i.e., a public mobile communication network other than any private network) outside the facility of the company. In this case, for users other than the staff members of the company, the communications provided by using the private network in the facility of the company is usually prohibited, or only limited services (such as an emergency call) can be provided by using the private network in the facility.
As another example of the private network, there is a base station apparatus (Home Node B) that can be installed in family homes. With the Home Node B, the right of using the Home Node B can be given to, for example, the family members only. However, the right of using the Home Node B may be temporarily given to a guest of the family members. In this case, the access (using) right is temporarily set in the user equipment of the guest so that the user equipment of the guest becomes a member of the private network.
A private network may also be referred to as “a CSG (Closed Subscriber Group) cell”, and the private network may include one or more the CSG cells. The term “CSG” refers to a group of the user equipment sets having an access (using) right to a specific private network, and the term “CSG cell” refers to a cell where each member of the CSG has a right to access.
As a method of limiting users so that only the limited users can use the private network, there is a known method of using a forbidden TA (Tracking Area) list. The forbidden TA List includes the tracking area identification of the private networks (TA-ID-PR). The forbidden TA list is individually transmitted to user equipment when the user equipment updates the registered TA (performs the TA update). The user equipment stores the forbidden TA list in its memory. When user equipment in the waiting mode (the idle mode) reselects the cell of the private network, the user equipment determines whether the tracking area identification (TA-ID-PR) of the private network is included in the forbidden TA list stored in the memory. As a result of the determination, if the tracking area of the cell reselected by the user equipment is included in the forbidden TA list, a process of waiting for a call performed by the user equipment in the cell is forbidden, thereby causing the user equipment to reselect another cell. The technique using the forbidden TA list as described above is described in, for example, Non Patent Document 1.
Non Patent Document 1: 3GPP, TS25.304, ver6.9.0